The present invention relates generally to a method for fabrication of semiconductor devices and more particularly a method for forming extremely fine patterns of the semiconductor devices.
In the metallization for intraconnections of semiconductor devices, the necessity for forming extremely fine patterns becomes increasingly important in the fabrication of high density integrated circuits. In general, evaporated films of aluminum have been used for metallization, but they produce various problems when etched to form extremely fine patterns. The so-called wet chemical etching methods employed in etching the aluminum films or layers are advantageous in that mass production is possible and the apparatus is simple to build, but these methods are not adoptable to form extremely fine patterns. When the aluminum layers are etched, they are coated in general with positive and negative photoresists. The negative photoresist coatings are excellent in adherance to the aluminum layers and in resistance to chemicals, but their resolution is not satisfactory and the formation of bridges tends to occur very frequently so that they cannot be used in forming extremely fine patterns wherein structual features are spaced apart from each other by a distance less than four microns.